Eco-friendly mangrove-derived nanocomposite coating for sustainable biofouling and corrosion protection in Persian Gulf field trials

Marine biofouling and corrosion impose major environmental and operational costs on maritime industries. This study aims to develop an eco-friendly, mangrove-derived nanocomposite coating that sustainably mitigates both challenges. Aluminum oxide and titanium dioxide nanoparticles were green-synthesized using Avicennia marina leaf extract and integrated with multi-walled carbon nanotubes (MWCNTs) into a polydimethylsiloxane (PDMS) matrix. Structural characterization (XRD, FTIR, FESEM-EDS, UV-Vis) confirmed uniform nanoparticle dispersion and hybrid formation with enhanced photocatalytic efficiency. The optimized 0.5 wt% Al₂O₃-TiO₂@MWCNT/PDMS coating exhibited superior antibacterial performance, achieving 96.5 % inhibition against S. aureus, 97.2 % against E. coli, and 95.8 % against P. aeruginosa, alongside 98.7 % anti-algal suppression of Nannochloropsis oculata. Corrosion current density reached as low as 0.008 μA/cm², while polarization resistance increased to 4750 kΩ·cm². Four-month field trials in the Persian Gulf demonstrated a 68 % reduction in fouling coverage relative to control PDMS panels. Through green synthesis and the exclusion of toxic biocides, this coating minimizes ecological risk and supports UN Sustainable Development Goals 9 and 14 by providing a scalable, durable, low-impact solution for marine infrastructure protection.